In auto sports, especially drag racing, operating an engine at its optimum range produces more horsepower, resulting in a quicker and faster racecar. One factor in optimizing an engine's output is adjusting the air fuel ratio to maintain an optimum valve over the entire time of use.
Mechanical fuel injection is commonly used in many racing applications, including draft racing. In a typical mechanically fuel injected engine, fuel is drawn from a tank or cell by an engine-driven injector pump, which delivers the main fuel feed to a barrel valve through a high-flow inline filter and shutoff valve. In a high performance application a high speed bypass valve is used. During a drag racing pass or run, mechanical fuel injection is hampered by having a lean starting line condition that turns to an overly rich condition by the end of the pass or run. A high-speed bypass provides a means for returning fuel the tank or cell increasing the air fuel ratio to avoid an overly rich condition at the finish line and leaning the motor out.
There are so called electronic lean outs known in the prior art, but they only open and close at predetermined times. These electronic lean outs do not use a signal from a sensor of the car to measure and react to actual conditions; instead they use timers to make adjustments on anticipated conditions. Therefore what is needed is a device that corrects instantly in real-time and will keep the air fuel ratio static in any mechanically fuel injected motor running on alcohol or gasoline during the course of a run.
A high-speed bypass (also known as a “high-speed lean-out”) is another check valve in a mechanical injection system. It opens and bleeds off fuel to a return circuit at the top end of the RPM range, thereby reducing fuel entering the engine and leaning out the air/fuel ratio (AFR). The shortcoming of a high-speed bypasses known in the prior art are that it is strictly mechanical and only provides for adjustment based on timers or a fixed setting which is insufficient to extract maximum power and efficiency from a mechanically fuel injected engine.
The most common type of high-speed bypass is a spring loaded “poppet” style that opens when a certain system pressure is achieved. Usually, the spring and shims inside can be changed so that the bypass opens at the desired pressure. Other types of bypasses can be actuated electronically or pneumatically and can be triggered directly by the driver, timers, RPM, etc. While many high performance or racing fuel systems employ a single, simple high-speed bypass, multiple simple high-speed bypasses can be used to achieve just the right fuel curve. Professional racers may use a plurality of lean-out and enrichment “events” during a pass.
The most practical reason to use a high-speed bypass is because at the top end of the RPM range, induction efficiency drops off sharply as the ability of the intake tract to pass air starts to diminish. At the top end of the RPM range the cylinders are not getting as full of air as they were in the lower RPM range. Because the mechanical injection system, with its positive displacement fuel pump, continues shooting fuel into the motor in proportion to RPM, it has no way to know that the air/fuel ration is getting richer as induction efficiency falls off and load on the engine decreases as the car accelerates through its transmission gears. A properly setup high-speed bypass will open up and pull some of that excess fuel away to correct for this condition.
The job of the high-speed bypass is to avoid an overly rich condition and keep the motor pulling hard all the way to the end of the pass. To date, all high-speed bypass valves known in the art are strictly mechanical and only provide for adjustment based on timers or a fixed setting. Therefore, what is needed is an electro-mechanical valve that can communicate with an air/fuel sensor and, using a circuit board acting as a computer, make real-time adjustments to the fuel flow to maintain a desired air/fuel ration for an entire pass.
Another reason to run the high-speed bypass is to change the air/fuel ratio altogether. A properly setup high-speed bypass can be setup to not only compensate for a drop in induction efficiency but also to shift the AFR to one that will produce the best MPH at the finish line.
Many sportsman or hobby racers will not run a high-speed bypass because it can be dangerous to engine parts if used improperly. Therefore what is needed is a device that can adjust fuel flow that monitors and uses an engine's air fuel ratio output to adjust the air fuel ratio being put into the engine to provide maximum results without the possibility for causing engine damage that is simple and easy to install.